Chemical compounds found in consumer goods, the environment, and materials that humans come into contact with on a regular basis pose a real and increasing threat to humans, animals, plant life, and water supplies. Such harmful compounds include Polycyclic Aromatic Hydrocarbons (PAHs), Bisphenol A (BPA), phthalates, Polychlorinated Biphenyls (PCBs), dioxins, organotins such as dibutyltin (DBT), triphenyltin (TphT), dioctyltin (DOT), hexachlorobenzene (C6Cl6) and tributyltin (TBT).
PAHs, also known as poly-aromatic hydrocarbons or polynuclear aromatic hydrocarbons, are potent atmospheric pollutants that consist of fused aromatic rings and do not contain heteroatoms or carry substituents. The term polynuclear aromatics is now considered obsolete and is not recognized as valid by either the IUPAC or the ACS. Naphthalene is the simplest example of a PAH. PAHs occur in oil, coal and tar deposits, and are produced as byproducts of fuel burning (whether fossil fuel or biomass). As pollutants, PAHs are of concern because some PAHs have been identified as carcinogenic, mutagenic and teratogenic. PAHs are also found in cooked foods. PAHs in consumer products and foods can originate from various sources including wood stoves and grills, charcoal grills, railroad ties, marine pilings, utility poles, burning trash, diesel engines, extender oils that are added to rubber materials to achieve the desired material properties, and soot, which is added to elastomers to achieve the required properties of the material. Consumers are exposed to PAHs not only by skin contact with consumer products but also through food, inhalation of contaminated air, and tobacco smoke. The Toxicology Section of the German Society for Experimental and Clinical Pharmacology and Toxicology (DGPT) provides estimates of the daily intake of Benzo[a]Pyrene (BaP) (as the reference compound for PAH mixtures) amongst others as follows: dietary intake 0.2 up to 0.5 μg and inhalation from tobacco smoke 0.4 μg. The World Health Organization (WHO) indicates an average daily intake for the general population of 0.001-0.005 μg/kg bodyweight. The Scientific Committee on Food (SCF) indicates a maximum daily intake of 0.42 μg/person, which approximately corresponds to 0.006 μg per kg bodyweight.
Studies have shown that high levels of PAHs are found, for example, in meat cooked at high temperatures such as grilling or barbecuing, and in smoked fish. PAHs were evaluated by the International Programme on Chemical Safety (IPCS), the Scientific Committee on Food (SCF) and by the Joint FAO/WHO Expert Committee on Food Additives (JECFA). SCF concluded that 15 PAHs, namely benz[a]anthracene, benzo[b]fluoranthene, benzo[j]fluoranthene, benzo[k]fluoranthene, benzo[ghi]perylene, benzo[a]pyrene, chrysene, cyclopenta[cd]pyrene, dibenz[a,h]anthracene, dibenzo[a,e]pyrene, dibenzo[a,h]pyrene, dibenzo[a,i]pyrene, dibenzo[a,l]pyrene, indeno[1,2,3-cd]pyrene and 5-methylchrysene show clear evidence of mutagenicity/genotoxicity in somatic cells in experimental animals in vivo and, with the exception of benzo[ghi]perylene, have also shown clear carcinogenic effects in various types of bioassays in experimental animals.
Polycyclic aromatic hydrocarbons are lipophilic, meaning they mix more easily with oil than water. The larger compounds are less water-soluble and less volatile. Because of these properties, PAHs in the environment are found primarily in soil, sediment and oily substances, as opposed to in water or air. However, they are also a component of concern in particulate matter suspended in air.
Natural crude oil and coal deposits contain significant amounts of PAHs, arising from chemical conversion of natural product molecules, such as steroids, to aromatic hydrocarbons. They are also found in processed fossil fuels, tar and various edible oils.
PAHs are one of the most widespread organic pollutants. In addition to their presence in fossil fuels they are also formed by incomplete combustion of carbon-containing fuels such as wood, coal, diesel, fat, tobacco, and incense. Different types of combustion yield different distributions of PAHs in both relative amounts of individual PAHs in which isomers are produced. Thus, coal burning produces a different mixture than motor-fuel combustion or a forest fire, making the compounds potentially useful as indicators of the burning history. Hydrocarbon emissions from fossil fuel-burning engines are regulated in developed countries. Used motor oils contain a significant concentration of PAHs.
PAHs generally have two or more fused or bridged aromatic rings. Smaller aromatic molecules, such as benzene and toluene, are not PAHs.
PAHs containing five- or six-membered rings are most common. PAHs composed only of six-membered rings are called alternant PAHs. Certain alternant PAHs are called benzenoid PAHs. These can be benzene rings interconnected with each other by single carbon-carbon bonds and with no rings remaining that do not contain a complete benzene ring.
PAHs containing up to six fused aromatic rings are often known as “small” PAHs, and those containing more than six aromatic rings are called “large” PAHs. Due to the availability of samples of the various small PAHs, the bulk of research on PAHs has been of those of up to six rings. The biological activity and occurrence of the large PAHs does appear to be a continuation of the small PAHs. They are found as combustion products, but at lower levels than the small PAHs due to the kinetic limitation of their production through addition of successive rings. In addition, with many more isomers possible for larger PAHs, the occurrence of specific structures is much smaller.
Naphthalene (C10H8), which consists of two coplanar six-membered rings sharing an edge, is another aromatic hydrocarbon. By formal convention, it is not a true PAH, though is referred to as a bicyclic aromatic hydrocarbon.
EU REACH Annex XVII has placed a restriction on the use of 8 PAHs in tires and extender oil. Tires will not be allowed to be placed on EU market if 8 PAHs exceed certain concentration thresholds listed in the following table. The restriction also applies to the marketing of tires in EU.
NameCASStructureLimitsBenzo[a]pyrene50-32-81 mg/kg Benzo[e]pyrene192-97-2 Benzo[a]anthracene56-55-3Sum of 8 PAHs <10 mg/kg Chrysene218-01-9REACH has designated ISO 21461 as standard testing method for 8 PAHs in tire. Benzo[b]fluoranthene205-99-2For extender oil, IP346 is used Benzo[k]fluoranthene207-08-9According to the ISO 21461, tires are compliant with the restriction on Benzo[j]fluorant205-82-3PAHs if the concentration of vulcanizates compound is not greater than 0.35% of Bay proton's limit. Dibenzo[a,h]anthrancene53-70-3
In addition to the EU restriction of 8 PAHs in tire and extender oil, Germany has decided on the mandatory Polycyclic Aromatic Hydrocarbons (16 PAHs) testing for the GS-certification process. The U.S. EPA has restricted 18 PAHs in consumer goods.
The limits for PAHs that must be met for materials of consumer goods are stated in the following table:
ParameterCategory 1Category 2Category 3Material in contact withMaterials with foreseeableMaterials with foreseeablefoodstuff, or materialscontact to skin for longercontact to skin up tointended to be put inthan 30 seconds (long-term30 seconds (short termthe mouth and toys forskin contact) and toysskin contact) or withoutchildren age of <36 monthsnot covered by category 1skin contactBenzo(a)pyreneNot detectable(<0.2)120mg/kgSum 18 PAHsNot detectable(<0.2)10200(EPA) mg/kg
A variety of technologies have been used to remove PAHs from various materials. Nevertheless, there remains a need for a PAH removal method that is commercially viable, that does not negatively affect the properties of the PAH-containing material, and is environmentally safe and effective at mild conditions.
U.S. Pat. No. 4,879,049 relates to a process of removing polycyclic aromatic hydrocarbons (PAH) by pre-coat vacuum filtration by forming a slurry and passing the slurry though a filter.
U.S. Pat. No. 5,045,206 relates to a process in which multi-ring aromatic hydrocarbons and/or toxins are selectively solvent-extracted from hydrocarbon feed streams by contacting the aromatics and/or toxins containing hydrocarbon stream with one side of a porous, non-selective partition barrier membrane while simultaneously contacting the other side of the membrane with an aromatics selective extraction solvent whereby the multi-ring aromatic hydrocarbons and/or toxins selectively migrate through the porous partition barrier membrane in response to the selective solvent. A preferred extraction solvent is ethylenediamine.
U.S. Pat. No. 5,880,325 relates to a process in which aromatic hydrocarbons are selectively extracted from lube oil stocks comprising mixtures of the same with non-aromatic hydrocarbons using tetramethyl sulfoxide as the extraction solvent. The oils so extracted are the heavier oils, i.e., those boiling above about 200° C. and identified as being at least lube base stock grade 60N and higher.
U.S. Pat. No. 6,923,915 relates to a process of purifying carbon nanomaterials, including fullerenes and fullerenic soot, using O-xylene, toluene, and o-dichlorobenzene, using a multiphase extraction process.
U.S. Pat. No. 7,118,906 relates to a process for removing three-ringed and/or four-ringed polycyclic aromatic hydrocarbons from sites contaminated therewith using white-rot lignin modifying fungus strain Flavodon flavus NRRL 30302.
U.S. Application No: 2011/0159160 relates to a process of removing PAHs using a low polarity medium by contacting the medium with the molecularly imprinted polymer.
Bisphenol A (BPA) and phthalates are organic compounds that are poorly soluble in water and have been used to make plastics for decades. Such plastics have been used to make food and drink packaging, e.g., water and infant bottles, and other consumer goods including adhesives and glues, electronics, agricultural adjuvants, building materials, personal-care products, medical devices, detergents and surfactants, packaging, children's toys, modeling clay, waxes, paints, printing inks and coatings, pharmaceuticals, food products, and textiles, compact discs, impact-resistant safety equipment, and medical devices. Other sources include epoxy resins used as lacquers to coat metal products such as food cans, bottle tops, and water supply pipes. Some dental sealants and composites may also contain BPA and/or phthalates. Bisphenol A is a weak endocrine disruptor, which can mimic estrogen and may lead to negative health effects including obesity, neurological issues, thyroid function, cancer, reproductive system and genital changes, miscarriages, and heart disease. Phthalates and phthalate esters are used as plasticizers in a large variety of products, from enteric coatings of pharmaceutical pills and nutritional supplements to viscosity control agents, gelling agents, film formers, stabilizers, dispersants, lubricants, binders, emulsifying agents, and suspending agents. Phthalates have been shown to change hormone levels and linked to birth defects, cancer, endocrine disruption, obesity, and metabolic problems. BPA and phthalates are easily released into the environment because there is no covalent bond between the phthalates and plastics in which they are mixed.
Polychlorinated Biphenyls (PCBs) belong to a broad family of man-made organic chemicals known as chlorinated hydrocarbons. In the United States, PCBs were domestically manufactured from 1929 until their manufacture was banned in 1979. They have a range of toxicity and vary in consistency from thin, light-colored liquids to yellow or black waxy solids. Due to their non-flammability, chemical stability, high boiling point, and electrical insulating properties, PCBs were used in hundreds of industrial and commercial applications including electrical, heat transfer, and hydraulic equipment; as plasticizers in paints, plastics, and rubber products; in pigments, dyes, and carbonless copy paper; and many other industrial applications.
Products that may contain PCBs include: transformers and capacitors, other electrical equipment including voltage regulators, switches, reclosers, bushings, and electromagnets, oil used in motors and hydraulic systems, old electrical devices or appliances containing PCB capacitors, fluorescent light ballasts cable insulation, thermal insulation material including fiberglass, felt, foam, and cork, adhesives, tapes, oil-based paint, caulking, plastics, carbonless copy paper, and floor finish.
Once in the environment, PCBs do not readily break down and therefore may remain for long periods of time cycling between air, water, and soil. PCBs can be carried long distances and have been found in snow and sea water in areas far away from where they were released into the environment. As a consequence, PCBs are found all over the world. In general, the lighter the form of PCB, the further it can be transported from the source of contamination. PCBs can accumulate in the leaves and above-ground parts of plants and food crops. They are also taken up into the bodies of small organisms and fish. As a result, people who ingest fish may be exposed to PCBs that have bioaccumulated in the fish they are ingesting. PCBs have been demonstrated to cause cancer, as well as a variety of other adverse health effects on the immune system, reproductive system, nervous system, and endocrine system.
Dioxins are environmental pollutants. They have the dubious distinction of belonging to the “dirty dozen”—a group of dangerous chemicals known as persistent organic pollutants. Dioxins are of concern because of their highly toxic potential. The highest environmental concentrations of dioxin are usually found in soil and sediment, with much lower levels found in air and water. Experiments have shown they affect a number of organs and systems. Once dioxins have entered the body, they endure a long time because of their chemical stability and their ability to be absorbed by fat tissue, where they are then stored in the body. Their half-life in the body is estimated to be seven to eleven years. In the environment, dioxins tend to accumulate in the food chain. The higher in the animal food chain one goes, the higher the concentration of dioxins.
The chemical name for dioxin is: 2,3,7,8-tetrachlorodibenzo para dioxin (TCDD). The name “dioxins” is often used for the family of structurally and chemically related polychlorinated dibenzo para dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs). Certain dioxin-like polychlorinated biphenyls (PCBs) with similar toxic properties are also included under the term “dioxins”. Some 419 types of dioxin-related compounds have been identified but only about 30 of these are considered to have significant toxicity, with TCDD being the most toxic.
Dioxins are mainly by products of industrial processes but can also result from natural processes, such as volcanic eruptions and forest fires. Dioxins are unwanted by products of a wide range of manufacturing processes including smelting, chlorine bleaching of paper pulp and the manufacturing of some herbicides and pesticides. In terms of dioxin release into the environment, uncontrolled waste incinerators (solid waste and hospital waste) are often the worst culprits, due to incomplete burning. Technology is available that allows for controlled waste incineration with low emissions.
Although formation of dioxins is local, environmental distribution is global. Dioxins are found throughout the world in the environment. The highest levels of these compounds are found in some soils, sediments and food, especially dairy products, meat, fish and shellfish. Very low levels are found in plants, water and air.
Extensive stores of PCB-based waste industrial oils, many with high levels of PCDFs, exist throughout the world. Long-term storage and improper disposal of this material may result in dioxin release into the environment and the contamination of human and animal food supplies. PCB-based waste is not easily disposed of without contamination of the environment and human populations. Such material needs to be treated as hazardous waste.
In July 2007, the European Commission issued a health warning to its Member States after high levels of dioxins were detected in a food additive—guar gum—used as thickener in small quantities in meat, dairy, dessert or delicatessen products. The source was traced to guar gum from India that was contaminated with pentachlorophenol (PCP), a pesticide no longer in use. PCP contains dioxins as contamination.
In 1999, high levels of dioxins were found in poultry and eggs from Belgium. Subsequently, dioxin-contaminated animal-based food (poultry, eggs, pork), were detected in several other countries. The cause was traced to animal feed contaminated with illegally disposed PCB-based waste industrial oil.
In March 1998, high levels of dioxins in milk sold in Germany were traced to citrus pulp pellets used as animal feed exported from Brazil. The investigation resulted in a ban on all citrus pulp imports to the EU from Brazil.
Another case of dioxin contamination of food occurred in the United States of America in 1997. Chickens, eggs, and catfish were contaminated with dioxins when a tainted ingredient (bentonite clay, sometimes called “ball clay”) was used in the manufacture of animal feed. The contaminated clay was traced to a bentonite mine. As there was no evidence that hazardous waste was buried at the mine, investigators speculate that the source of dioxins may be natural, perhaps due to a prehistoric forest fire.
Short-term exposure of humans to high levels of dioxins may result in skin lesions, such as chloracne and patchy darkening of the skin, and altered liver function. Long-term exposure is linked to impairment of the immune system, the developing nervous system, the endocrine system and reproductive functions. Chronic exposure of animals to dioxins has resulted in several types of cancer. TCDD was evaluated by the WHO's International Agency for Research on Cancer (IARC) in 1997. Based on animal data and on human epidemiology data, TCDD was classified by IARC as a “known human carcinogen.”
Due to the omnipresence of dioxins, all people have background exposure and a certain level of dioxins in the body, leading to the so-called body burden. Current normal background exposure is not expected to affect human health on average. However, due to the high toxic potential of this class of compounds, efforts need to be undertaken to reduce current background exposure.
Hexachlorobenzene is a fungicide that was used as a seed treatment until it was banned globally under the Stockholm Convention on persistent organic pollutants. It was also used in the production of rubber, aluminum, and dyes and in wood preservation. Hexachlorobenzene is formed as a byproduct during the manufacture of other chemicals. Chronic oral exposure to hexachlorobenzene in humans results in a liver disease with associated skin lesions. Animal studies have reported cancer of the liver, thyroid, and kidney from oral exposure to hexachlorobenzene. Studies have also shown hexachlorobenzene to be associated with diabetes.
Organotins are highly toxic and widely distributed environmental chemicals. Dibutyltin (DBT) is used as stabilizer in the production of polyvinyl chloride plastics, and it is also the major metabolite formed from tributyltin (TBT) in vivo. DBT is immunotoxic, however, the responsible targets remain to be defined. Due to the importance of glucocorticoids in immune-modulation, we investigated whether DBT could interfere with glucocorticoid receptor (GR) function.
The most abundant organotin in the environment is tributyltin (TBT), a molluscicide and fungicide widely used as an antifouling paint for boat and fish nets, and thus is dispersed into the marine environment. TBT interferes with reproduction in marine animals, inducing imposex (superimposition of male sexual characters in females) in gastropod mollusks, an effect used to measure TBT pollution in sea-water. In vivo, TBT is mainly metabolized to DBT in the liver, involving cytochrome P450 enzymes. n-Butyltin trichloride is used in the production of tin dioxide layers on glass bottles by chemical vapor deposition. Tributyltin oxide has been extensively used as a wood preservative. Uses include wood preservation, antifouling pesticide in marine paints, antifungal action in textiles and industrial water systems, such as cooling tower and refrigeration water systems, wood pulp and paper mill systems, and breweries.
Tributyltin oxide is the most widely used compound in TBT-containing commercial products. Tributyltin compounds are moderately to highly persistent organic pollutants that biomagnify up the marine predators' food net. One common example is leaching of TBT from marine paints into the aquatic environment, causing irreversible damage to the aquatic life. Tributyltin has also been linked to obesity in humans, as it triggers genes that cause the growth of fat cells. TBT compounds are also used as marine anti-biofouling agents. Concerns over toxicity of TBT and TPT compounds (some reports describe biological effects to marine life at a concentration of 1 nanogram per liter) have led to a worldwide ban by the International Maritime Organization.
Triorganotins are very toxic. Tri-n-alkyltins are phytotoxic and therefore cannot be used in agriculture. Depending on the organic groups, they can be powerful bactericides and fungicides. Tributyltins are used as industrial biocides, e.g., as antifungal agents in textiles and paper, wood pulp and paper mill systems, breweries, and industrial cooling systems. Tributyltins are also used in marine anti-fouling paint. Triphenyltins are used as active components of antifungal paints and agricultural fungicides. Other triorganotins are used as miticides and acaricides. Organotin compounds are used commercially in a wide range of applications such as biocides, insecticides, chemical intermediates and as catalysts.
Environmental concentrations of TBT and TPT vary depending upon how, when and where compounds are used. Up to 1.58 μg/l (sea water) and 7.1 μg/l (fresh water) of TBT, and nearly 200 ng/l of TPT have been detected in some bay areas or marinas with many boats treated with organotin-based antifouling-paints.
TBT and TPT are sparingly soluble in water and easily adsorbed to particulate matter in the aquatic environment. Hence they are accumulated in sediment where they are relatively persistent and are taken up by the benthic organisms such as clams. TBT and TPT are accumulated in fish and other aquatic organisms with bioconcentration factors of 102-104.
TPT and TBT produce various health effects in laboratory mammals, including effects on the immune system, such as decreases in immunoglobulin concentrations, lymphopenia, and thymus or splenic atrophy in rats and mice, reproductive/developmental effects
Due to the health risks associated with the class of harmful compounds, there was a need to reduce levels of such harmful compounds that has been met by the invention described herein.